Liquid dispensers which employ a wick to convey a liquid or a volatile material from a container to an emanator are designed to slowly diffuse a liquid through a wick. The liquid may be a volatile scent-producing liquid, as in the case of air fresheners. In the case of wick type air fresheners, the scent-producing liquid is conveyed from a container, by means of capillary action through a wick, to an emanator, which diffuses the scent-producing liquid into the atmosphere in the form of a vapor, by the process of evaporation.
In order to be effective, the wick type dispensing device must provide the desired fragrance at a slow uniform rate, over an extended period of time. Prior art wick type air fresheners experience problems with poor flow of liquids and weight loss of fragrance, and health issues involving aspiration or swallowing of the fragrances.
The International Fragrance Association (IFRA) was created in 1973, primarily to take into account the vast quantity of safety information being generated by the Research Institute for Fragrance Materials (RIFM). IFRA took the safety data being generated by RIFM, and other data from different sources, and started to formulate guidelines for the safe use of fragrance ingredients where RIFM and others had identified potential hazards in their testing programs. IFRA Guidelines either ban or restrict ingredients in fragrance compounds and, therefore, in the final products, where safety testing had shown there to be a potential hazard of aspiration or swallowing.
U.S. Pat. No. 6,435,423 discloses a device for the diffusion of a volatile active ingredient with a hydrophobic medium, a volatile active ingredient and a superabsorbent substance. The superabsorbent substance is capable of forming a gel with the hydrophobic medium and is susceptible of enclosing the volatile active ingredient within the gel to permit diffusion of the volatile ingredient from the gel upon exposure to air. A wick is used to supply the gel with solvent so that the gel is continually moistened.
U.S. Pat. No. 4,549,693 discloses a dispenser, comprised of a two part circular housing, containing a round absorbent pad, whereby the effective aperture openings in the housing are controlled by an up and down sliding motion, bringing the apertures in each part, in and out of register.
U.S. Pat. No. 4,306,679 discloses a dispenser with a two part housing, containing a round absorbent pad, whereby the effective aperture openings in the housing are controlled by a twisting motion, bringing the apertures in each part, in and out of register.
U.S. Pat. No. 4,280,649 discloses an aperture control consisting of a two part rectangular carton, sliding up and down to provide a means to vary the aperture size.
All of the above patents describe a method to control the rate of diffusion of a scent-producing liquid into the atmosphere, by control of the aperture size in the air freshener container.
Wick in the bottle type of air freshener units have traditionally suffered from a lack of adequate control, to deliver a scent-producing liquid at a slow constant rate over an extended period of time. There remains a need for an improved dispensing device, capable of slow controlled dispensing and diffusion of fragrances and flavors which reduce aspiration or swallowing of the fragrance and further reduce spillage problems.